Go to /usr/share/themesCopy Minty folderGo to /home folderClick View > Show hidden files If .themes folder is not there, create it (note the . dot)Paste the copy of Minty folder in .themesRename the copy of Minty to Minty-new (for example)

Open /home/username/.themes/Minty-new/cinnamonOpen cinnamon.csschange this top section:

Doing it this way - copying the original folder, renaming and working on it in /home/username/.themes makes it easy to go to Cinnamon Settings and change back to the original Minty if you don't like your changes in Minty-new.

Very basic, but hopefully some people more experienced with themes with chime in with some more tips ...